1. Field of the Invention
This invention relates to the processing of video data and, in particular, to video data processing systems and methods, for use with low frame rate video systems, that are flexible, that can be implemented compactly and inexpensively, and that result in improved display of motion and reduced noise in the processed video data.
2. Related Art
Generally, a video display of an image including motion must be updated with new video data at or above a particular frequency in order to produce an acceptable video display. A variety of real-time video applications, such as remote surveillance and identification systems and teleconferencing systems, require real-time transmission of digital video data from one location to another and display of the data at the new location. In such systems, it has been difficult to transmit the video data (or, "image data") over conventional transmission lines (e.g., conventional telephone lines) at a rate that is fast enough to enable the video display to be updated with new video data at a rate that produces an acceptable display of moving images. The problem has been exacerbated by the representation of video images with increasingly larger amounts of data (in an effort to produce higher quality displays), since such increased amounts of video data require increased data transmission rates to update the video display with new video data at a given rate.
High speed data transmission systems, such as T1, T3 and ISDN, may be employed to address the above problem. However, high speed data transmission systems are expensive, are not available in some areas, and can be inefficient.
Data compression techniques have also been used to address the above problem by decreasing the amount of data required to represent each video image, thereby reducing the amount of video data transmitted over the transmission line and effectively increasing the data transmission rate. However, to the extent that data compression techniques are useful in solving the problem, these techniques also introduce other problems which affect the quality of the display, such as spurious random image variations that appear as noise in the displayed image. Additionally, as the incidence of motion in the image increases, the utility of data compression decreases, since the increasing presence of motion reduces the degree to which it is possible to compress the data.
Thus, notwithstanding these and other attempts to address the problem of transmitting data for real-time, full motion, remote video applications, there still exists a conflict between achievable data transmission rates and the information content required per unit of time for satisfactory video display. The problem is particularly severe when the data is transmitted over a conventional telephone line or when color video data is transmitted.